Monday, November 12, 2012

Weather at the Grand Canyon

Weather at the Grand Canyon varies greatly. The four seasons bring an array of conditions depending on your location. The driest conditions and lowest humidity exist during late spring and early summer. Winter and fall bring heavy rain, thunderstorms, and harsh snow storms as seen in the following pictures.
http://www.bing.com/images/search?q=rain+at+the+grand+canyon&view=detail&id=58574A7D0ED9C88EC39A207A3AB22CCC914DFDF7




 http://www.bing.com/images/search?q=thunderstorms+at+the+grand+canyon&view=detail&id=7AC3645052D9A0BDD5D7C31585EAA6B3BEB6E05D
 
 
 http://www.bing.com/images/search?q=snowfall+at+the+grand+canyon&view=detail&id=645F910CAE493C543F4699CD42DA6A70309DFD3F

The North Rim of the canyon has experienced temperatures of -22 °F, while the south Rim of the canyon has experienced 120°F on several occasions. Along with temperature, precipitation around the canyon varies widely. The North Rim of the canyon averages 25.8” of rain a year, while the South Rim has areas that receive less than 1” of moisture a year. Precipitation depends on cloud formation and the production of rain through a series of atmospheric conditions and adiabatic processes.  These processes along with the wide range of precipitation occur because air masses in the atmosphere exist under different conditions. Air masses exist as stable, unstable, or in between in conditional stability.
http://www.paragonair.com/public/docs/AdvCircs/AC00-06A_AvWx/AC00-6A_ch06.html
Notice in this picture, the stable air mass is resisting vertical movement, while the unstable air is rising. Unstable air will rise in the presence and subsequent removal of force. Conditional stability happens when the air mass is neither stable nor unstable. This air mass will behave stable, but can change to unstable when force is applied.
 
 
Air masses rise when warm, but begin to descend once cool. The high temperatures found at the canyon allow for warm air parcels to exist and rise. Depending on the condition of the air mass itself, the air parcels may rise leading to changes in temperature and cloud formation. 
 
 
In this picture, the red denotes warm air. Notice how the warm air rises. If the Dew Point (100%relative humidity ) is reached, clouds begin to form and can return what once left as warm air and water vapor, as moisture and cool air back to the ground. http://www.vivoscuola.it/us/rsigpp3202/umidita/lezioni/form.htm
 
 
 
The above picture depicts orographic lifting and the rainshadow effect. In the above picture, the air mass encounters a barrier that pushes the air upward along what is called the windward side. The air is moved high enough for condensation to occur bringing about precipitation. As the air begins to descend onto the leeward side of the mountain, all the precipitation has been left behind on the windward side. This leaves nothing but dry warm descending air. This process creates the driest of the areas around the canyon as shown in the following picture.


Sources
http://blackboard.cuonline.edu/webapps/portal/frameset.jsp?tab_tab_group_id=_2_1&url=%2Fwebapps%2Fblackboard%2Fexecute%2Flauncher%3Ftype%3DCourse%26id%3D_70686848_1%26url%3D






 

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